VDC is an impurity formed during the manufacture of I-141b, a replacement for trichlorofluoromethane as a blowing agent. Since VDC is a suspected carcinogen, a method for its removal is needed, desirably to levels below 500 ppm. Separation by conventional distillation means is extremely difficult, however, since VDC boils at 31.degree. C. and I-141b boils at 32.degree. C.
Removal of VDC by reacting it with chlorine under ultraviolet radiation is disclosed in U.S. Pat. No. 4,948,479, but this requires the consumption of an extra raw material (chlorine) and loss of product to reaction.
While liquid-liquid extraction has been reported in U.S. Pat. No. 4,031,148 for separating chlorinated hydrocarbons by the use of water-miscible solvents and 0-50% water, applicant is not aware of literature which discloses liquid-liquid extraction for separating VDC from HCFC's (hydrochlorofluorocarbons) such as I-141b.